Sand Dunes of the Southwest

Algodones Dunes, CA

Algodones Dunes

Olsen Family Photo

This large dune field is located in the extreme southeast corner of California about 17 miles west of Yuma, Arizona. The long narrow dune system extends for approximately 45 miles in a 5- to 8-mile wide band. The dunes extend along a northwest-southeast line. The name "Algodones Dunes" refers to the entire geographic feature, while the portion that is administered by the Bureau of Land Management is known as the Imperial Sand Dunes Recreation Area. This area is also sometimes called the Glamis Dunes, after the adjacent town of Glamis, CA.

The Algodones Dunes complex covers 1,000 square miles of Sonoran Desert, making it the largest dune system in the United States. Some people think the sand may have blown in from beaches to the west. However, many geologists believe these dunes were formed by windblown sands from the site of ancient Lake Cahuilla. A prehistoric predecessor of the Salton Sea, this large body of water once filled the Imperial and Coachella Valleys when the Colorado River ran a slightly more westerly course. According to local Indian legend, Lake Cahuilla gradually shrank in size until it became completely dry sometime between 1450-1600.

Lake Cahuilla

The sand was carried to its present location by the prevailing northwesterly and westerly winds. This process continues today, so the Algodones is an active dune system in which the sand is constantly changing. The largest dunes in the center rise to heights of over 300 feet, while smaller dunes line the edges. The dunes are migrating to the southeast at a rate of approximately one foot per year. An extension of these dunes also lies across the Colorado River in the vicinity of Yuma, AZ.

Despite the shifting sands, dry climate, and extreme temperatures, the Algodones dunes are amazingly biologically diverse for their barren appearance. Although the area's rainfall averages only 2 inches annually, washes draining from the nearby Chocolate Mountains flow westward to the edge of the dunes, which act like a natural dam. This water source supports mesquite, desert willow, ironwood, paloverde, and smoke trees. The Algodones Dunes are home to 42 endemic insect species including scarab beetles, weevils, beetles, wasps, and bees. Endemic plants include the Algodones Sunflower, Dune Buckwheat, Sand Food, and Peirson's Milkvetch, which is listed as threatened under the Endangered Species Act. Spring wildflowers include the dune primrose and sand verbena.

The Algodones Dunes are bordered on the west by the Coachella Canal, and on the right by a Southern Pacific railroad track. The dunes taper to a point at the northern end, and they extend across the Mexican border at the southern end. The dunes are crossed by two highways - SR78 and I-8 - both of which provide easy access to the dunes. The section of smaller dunes north of Highway 78 near the Chocolate Mountains is set aside as a wilderness area. Also off Highway 78 is a roadside overlook providing scenic panoramic views of the sand dunes, Chocolate Mountains, and Imperial Valley farmlands.

The larger dunes south of Highway 78 are a favorite location for off-highway vehicle (OHV) enthusiasts, and the dunes get extremely crowded on winter holiday weekends. But when the herds of ATVs, buggies, jeeps, and trucks leave the area, if you go there on a weekday after the wind has blown for a couple of days, it will have removed all traces of people ever having been there. Such is the dynamic nature of sand dunes.

The All-American Canal cuts through the dunes near I-8. This section of the All-American requires constant maintenance because of sand being blown into the canal. Visiting the site in February 2010, an extensive dredging operation was observed in progress. The canal has also recently been realigned to avoid the worst areas of dune-sand invasion.

Plank Road

Olsen Family Photo

Just south of I-8, near the Grays Well Road exit, there is a small surviving remnant of a historic wooden plank road that once spanned the approximately 6-mile width of the dunes, literally "floating" on top of the sand. Built in 1916, the oak plank road was made in 30-feet sections so each could be moved by a team of horses or mules when it became covered with drifting sand. This road was used by travelers driving between Yuma and San Diego for ten years before being replaced by a paved highway in 1926. (The Visitor Center at Yuma Crossing/Yuma Quartermaster State Historic Park also features an exhibit of a Model T Ford on a preserved piece of this wooden plank road.)

During World War II, the Algodones Dunes were part of General George S. Patton's California-Arizona Maneuver Area. This must have been an ideal location for training his troops to endure the harsh conditions of the Sahara Desert in northern Africa. Daytime temperatures at the Algodones Dunes range from 39F in the winter to 120C in the summer. Sand surface temperatures can exceed 150F in summer. Wind speeds can reach 60 mph, making visibility difficult because of blowing sand.

Imperial Sand Dunes

Border Patrol photo

In 2008, a border fence was constructed across the dunes to separate Mexico from the United States. The fence is 11 miles long and 15 feet high, its 30-foot sections of steel beams designed to sit on top of the sand and allow sand to blow through it. When drifts of sand build up against the fence, the Border Patrol can use a crane to raise the fence back up to the surface. Before the fence was built, drug smugglers and illegal immigrants had easy access to I-8, which is less than a half mile from the border. All they had to do is hop in an off-road vehicle and drive across the dunes.

Algodones Dunes

Google Earth image


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Website design and content (c)2010 by Peter Olsen. This educational unit study was my PVCC honors project for GPH 211 Landform Processes.